1. Field of the Invention
The present invention relates to an aperture fluorescent lamp manufacturing method, which is suitably used for manufacturing a relatively small-diameter aperture fluorescent lamp having an aperture portion opened for light projection in a part of a straight glass tube in the axial direction, a manufacturing method of a surface illuminator provided with an aperture fluorescent lamp, a relatively small-diameter aperture fluorescent lamp, a surface illuminator provided with an aperture fluorescent lamp, a liquid crystal display device provided with the surface illuminator, and an electronic device provided with the liquid crystal display device.
The present application claims priority of Japanese Patent Application No.2000-215239 filed on Jul. 14, 2000, which is hereby incorporated by reference.
2. Description of the Related Art
Conventionally, an aperture fluorescent lamp has been available, which emits light in a concentrated manner from an opening portion (referred to as an aperture portion, hereinafter) for light projection provided in a part of a straight glass tube in the axial direction. This aperture fluorescent lamp has widely been used as a backlight source, for example, in a liquid crystal display device for OA (Office Automation) equipment. The aperture fluorescent lamp has also been used as a document illumination light source in a facsimile, a copying machine, or the like.
With regard to a method for manufacturing such an aperture fluorescent lamp, technologies that have been available include, for example, one disclosed in Japanese Patent Laid-open No. Hei 6-260088 for forming an aperture portion by using a method of scraping off a phosphor with a rod (referred to as a first conventional technology), and one disclosed in Japanese Patent Laid-open No. Hei 9-306427 for forming an aperture portion with a photo mask (referred to as a second conventional technology).
In the case of the first conventional technology, as shown in FIG. 30, first, a phosphor is coated on the inner surface of a cylindrical glass tube 101 having both ends opened to form a phosphor layer 102. Then, a metal rod 104 having a brush 103 on a tip portion containing a magnetic substance like that shown in FIG. 31 is inserted from one opening of the glass tube 101 as shown in FIG. 32, and guided by a magnet 105 from the outside of the glass tube 101. The brush 103 is moved in pressed state to the phosphor layer 102 to scrape off the phosphor in a predetermined region, thus forming an aperture portion 106 as shown in FIG. 33.
In the case of the second conventional technology, first, a mixture of a photo-curing resin and a phosphor is coated inside a glass tube. Then, a photo mask (not shown) is attached to a predetermined region, in which an aperture portion 106 is formed, and irradiated with ultraviolet rays. Then, the photo mask is removed, an insensitive portion is washed off with hot pure water, and then dried and subjected to heating and burning. Then, a phosphor layer 102 is formed on other than the aperture portion 106 as shown in FIG. 33.
In addition, in both ends of an aperture fluorescent lamp 107 manufactured in the foregoing manner, as shown in FIG. 34, positioning pieces 108 for aligning an orientation of the aperture portion 106 at backlight assembly are attached.
To manufacture, for example, a backlight 115 of a sidelight type, by using the aperture fluorescent lamp 107 having such positioning pieces, as shown in FIGS. 35 and 36, by fitting each of the positioning pieces 108 in a groove of a reflector 109 groove-shaped in section for reflecting and guiding light emitted from the aperture fluorescent lamp 107 to a light guide plate 112, the aperture fluorescent lamp 107 is attached to the reflector 109. Then, the reflector 109 having the aperture fluorescent lamp 107 attached thereto is fixed onto a rear case 110. At this time, the aperture portion 106 is positioned to face a direction (horizontal direction in FIGS. 35 and 36) roughly parallel to the top surface of the rear case 110 as a casing.
On the rear case 110, a reflection sheet 111, the light guide plate 112, and an optical correction sheet 113 are sequentially laminated, and then covered with a center case 114, thus completing the backlight 115.
To manufacture a directly-below backlight 116 of a directly-below type by using aperture fluorescent lamps 107, as shown in FIG. 37B, a plurality of aperture fluorescent lamps 107, 107 . . . , are positioned and disposed on the bottom part of a reflection plate 117 such that the aperture portions 106 can face a direction (directly above in the drawing) vertical to a light emission surface. Above the aperture fluorescent lamps 107, 107 . . . , a diffusion plate 118 is attached for obtaining a surface light source by diffusing emitted or reflected light.
With regard to the method for manufacturing the aperture fluorescent lamp, in the case of the first conventional technology, to manufacture a relatively small-diameter aperture fluorescent lamp, the brush 103 and the metal rod 104 must be formed thin. However, if the metal rod 104 is formed thin, the metal rod 104 is fluttered or bent, damaging the phosphor layer 102 other than the aperture portion 106. Consequently, it is practically difficult to manufacture a small-diameter aperture fluorescent lamp having an inner diameter of 3 mm or less.
In addition, to manufacture an aperture fluorescent lamp having a long glass tube length, length of the metal rod 104 must be made long. Thus, the metal rod 104 is fluttered or bent, damaging the phosphor layer 102 other than the aperture portion 106. Consequently, it is also difficult to manufacture an aperture fluorescent lamp having the long glass tube length.
Therefore, in the backlight as a surface illuminator using the aperture fluorescent lamp manufactured by the foregoing method, for example, as shown in FIG. 36, the size of a housing part 109h (FIG. 36) of the aperture fluorescent lamp 107, which is formed by being surrounded with the rear case 110, cannot be reduced. In other words, a longitudinal width a0 including clearances b0 and c0 in upper and lower sides of the aperture fluorescent lamp 107 and a transverse width d0 cannot be reduced. In addition, a width e0, which is regulated by the transverse width d0, of a frame part of the center case 114 above the aperture fluorescent lamp 107 cannot be reduced. Consequently, it is impossible to reduce not only weight of the aperture fluorescent lamp 107 but also those of other members.
It can therefore be understood that there are difficulties of thinning, narrow frame formation, and weight reduction for the backlight using the aperture fluorescent lamp manufactured by the described manufacturing method.
Thus, there are also difficulties of thinning, narrow frame formation, and weight reduction for both of a liquid crystal display device using the backlight and an electronic device using such the liquid crystal display device.
In the case of the second conventional technology, in addition to mixture coating step, exposure, developing, and many other steps are necessary. Thus, much time, and labor must be expended, thereby causing an increase in cost.
Therefore, there are problems of high costs for the backlight 115 as a surface illuminator using the aperture fluorescent lamp 107 manufactured by the described manufacturing method, a liquid crystal display device using the backlight 115, and a device using such the liquid crystal display device.
In the foregoing positioning method of the aperture portion 106, the positioning pieces 108 as members dedicated for positioning are necessary in the manufacturing process of the aperture fluorescent lamp 107.
Thus, material and process costs are increased by attaching (adhering) of the positioning pieces 108, and there are difficulties of thinning, narrow frame formation, and weight reduction when the aperture fluorescent lamp 107 is incorporated in the backlight 115.
If the positioning pieces 108 are omitted, when the aperture fluorescent lamp 107 is attached to the reflector 109 or the center case 114, an assembling operator must check position of the aperture portion 106, and align its orientation, thus making positioning difficult. Since a member around the aperture fluorescent lamp 107 becomes to be a visual obstacle during orientation alignment, the aperture portion 106 cannot be correctly positioned, thus deteriorating yield.
In the case of the directly-below backlight 116 using the aperture fluorescent lamp 107, for example, in a direction (y axis direction in FIG. 37A) orthogonal to the axis of the aperture fluorescent lamp 107 in the upper surface (light emission surface) of the diffusion plate 118, luminance is highest in a position (Y=Y0 in FIG. 38) directly above the aperture fluorescent lamp 107, and the luminance is lowest near a position (Y=Ym) equidistant from the axes of the adjacent aperture fluorescent lamps 107 and 107, thus generating luminance uneveness.
Specifically, as shown in FIG. 38, compared with a distance L0 between the axis of the aperture fluorescent lamp 107 and a position Q0 (Y=Y0, and Z=Z0) directly above the aperture fluorescent lamp 107 in the backside of the diffusion plate 118, a distance Lm between the axis of the aperture fluorescent lamp 107 and a position Qm (Y=Ym, and Z=Z0) equidistant from the adjacent aperture fluorescent lamps 107 and 107 in the backside of the diffusion plate 118 is longer. Light is diffused and attenuated by an amount equal to such a difference in optical path lengths, making dark a part near the position Qm. Further, near the position Qm, light is obliquely directed from the aperture fluorescent lamp 107. Thus, the component of a light intensity in a direction (Z axis direction) vertical to the light emission surface of the light diffusion plate 118 becomes smaller than that of a light intensity in the position Q0 directly above the aperture fluorescent lamp 107.
Therefore, because of the directional characteristic (relation between the direction of radiation and luminance) of the aperture fluorescent lamp 107, a part directly above the aperture fluorescent lamp becomes bright, and the middle part equidistant from the adjacent aperture fluorescent lamps 107 and 107 becomes dark. As shown in FIG. 37A, the luminance F of light emitted from the diffusion plate 118 is changed in a wave shape in the Y-axis direction of the light emission surface. Consequently, luminance uniformity is deteriorated.
The above problem occurs even when a general lamp other than the aperture fluorescent lamp is used.
Thus, in the conventional art, as shown in FIG. 37B, by setting the distance L0 between the aperture fluorescent lamp 107 and the diffusion plate 118 to be sufficiently long (for example, L0=13 mm to 15 mm), and diffusing light at the diffusion plate 118, luminance uniformity must be adjusted to a level at which the backlight 116 can be used as a product. Consequently, the distance Lo cannot be set equal to a predetermined value or lower.
It can therefore be understood that there are difficulties of thinning and weight reduction in the case of the directly-below backlight 116.
In view of the above, it is an object of the present invention to provide an aperture fluorescent lamp manufacturing method capable of easily manufacturing even a relatively small-diameter aperture fluorescent lamp with high yield and at low cost.
It is another object of the present invention to provide a small-diameter aperture fluorescent lamp, a thin, narrow-frame, and lightweight surface illuminator, a liquid crystal display device having the surface illuminator, and an electronic device having the liquid crystal display device at low costs.
It is still another object of the present invention to provide a surface illuminator manufacturing method capable of accurately and easily positioning an aperture portion, improving yield, and contributing to thinning, narrow frame formation, weight reduction, and achievement of low cost.
It is still another object of the present invention to provide a surface illuminator capable of obtaining good luminance uniformity, a liquid crystal display device having the surface illuminator, and an electronic device having the liquid crystal display device.
According to a first aspect of the present invention, there is provided an aperture fluorescent lamp manufacturing method for forming an aperture portion opened for light projection by forming a phosphor layer on an inner surface of a glass tube, and then eliminating the phosphor layer in a predetermined region in an axial direction of the glass tube, including:
a member inserting step of inserting one selected from a thread-like member and a belt-like member having a predetermined surface roughness and a predetermined tensile strength into the glass tube having the phosphor layer formed therein; and
a phosphor exfoliating step of exfoliating a phosphor by sliding the one selected from the thread-like member and the belt-like member in relative displacement to the phosphor layer while the one selected from the thread-like member and the belt-like member is in contact by pressure with the phosphor layer formed in the predetermined region.
In the foregoing first aspect, a preferable mode is one wherein, in the member inserting step, an end of the one selected from the thread-like member and the belt-like member is inserted from one opening of the glass tube, and the one selected from the thread-like member and the belt-like member is sucked from an opposite opening.
Also, a preferable mode is one wherein, in the phosphor exfoliating step, the one selected from the thread-like member and the belt-like member is slid while the glass tube is bent to a side of forming the aperture portion.
Also, a preferable mode is one that further includes a glass tube rotating step of rotating the glass tube having the phosphor layer formed therein around an axis of the glass tube in a range of a predetermined angle, wherein the glass tube rotating step and the phosphor exfoliating step are executed alternately or simultaneously.
Also, a preferable mode is one that further includes a member rotating step of rotating the one selected from the thread-like member and the belt-like member around an axis of the glass tube in a range of a predetermined angle, wherein the member rotating step and the phosphor exfoliating step are executed alternately or simultaneously.
Also, a preferable mode is one that further includes a phosphor eliminating step of eliminating the phosphor exfoliated in the phosphor exfoliating step.
Also, a preferable mode is one wherein, in the phosphor eliminating step, the exfoliated phosphor is sucked from any one of the openings of the glass tube.
Also, a preferable mode is one wherein the one selected from the thread-like member and the belt-like member has flexibility, and predetermined concave and convex machining is executed at least in a portion brought into contact with the phosphor layer.
Also, a preferable mode is one wherein the one selected from the thread-like member and the belt-like member is made of an adsorbent material or an adhesive material for sticking the phosphor.
Also, a preferable mode is one wherein the thread-like member is made of fiber or metal.
Also, a preferable mode is one wherein a plurality of the belt-like aperture portions are formed in the axial direction of the glass tube.
According to a second aspect of the present invention, there is provided a method of manufacturing a surface illuminator including: an aperture fluorescent lamp having a glass tube, a pair of electrodes sealed to both ends of the glass tube, a phosphor layer formed on an inner surface of the glass tube, and an aperture portion formed by eliminating the phosphor layer in a predetermined region in an axial direction of the glass tube and opened for light projection; and a holding frame member for holding the aperture fluorescent lamp by a supporting member, including the steps of:
preparing the aperture fluorescent lamp having a tip part of a lead conductor, which is connected to the electrode, formed in a predetermined convex shape, and the supporting member having a concave or a hole part for fixing the aperture fluorescent lamp while the concave or the hole part is fitted to the tip part of the lead conductor to face a predetermined direction; and
fitting the tip part of the lead conductor in the concave or the hole part of the supporting member attached to the holding frame member, thus positioning the aperture fluorescent lamp in a predetermined posture.
According to a third aspect of the present invention, there is provided an aperture fluorescent lamp including: a phosphor layer formed on an inner surface of a glass tube; and
an aperture portion formed by eliminating the phosphor layer in a predetermined region in an axial direction of the glass tube and opened for light projection, wherein
a plurality of the aperture portions, each having a belt-like shape, are formed.
In the foregoing third aspect, a preferable mode is one wherein number of the aperture portions is two, the aperture portions being disposed to be separated from each other by a predetermined angle gap around an axis of the glass tube.
According to a fourth aspect of the present invention, there is provided a surface illuminator including:
an aperture fluorescent lamp having a phosphor layer formed on an inner surface of a glass tube, and an aperture portion formed by eliminating the phosphor layer in a predetermined region in an axial direction of the glass tube and opened for light projection; and
a light guide unit formed by sequentially laminating at least a reflection sheet and a light guide plate, and adapted to take in light emitted from the aperture fluorescent lamp from a surface facing the aperture fluorescent lamp and guide the light in a direction roughly perpendicular to a light emission surface of the surface illuminator, wherein
the reflection sheet is extended to at least a bottom part side of the aperture fluorescent lamp.
In the foregoing fourth aspect, a preferable mode is one wherein the reflection sheet is wound around the aperture fluorescent lamp and extended to a light emission surface side of the aperture fluorescent lamp.
According to a fifth aspect of the present invention, there is provided a surface illuminator including:
an aperture fluorescent lamp having a phosphor layer formed on an inner surface of a glass tube, and an aperture portion formed by eliminating the phosphor layer in a predetermined region in an axial direction of the glass tube and opened for light projection;
a light guide unit formed by sequentially laminating at least a reflection sheet and a light guide plate, and adapted to take in light emitted from the aperture fluorescent lamp from a surface facing the aperture fluorescent lamp and guide the light in a direction roughly perpendicular to a light emission surface of the surface illuminator; and
a reflection member disposed in at least a light emission surface side of the aperture fluorescent lamp.
In the foregoing fourth and fifth aspects, a preferable mode is one that further includes a holding frame member for holding at least one of the aperture fluorescent lamp and the light guide unit, wherein the holding frame member and the aperture fluorescent lamp are disposed to be brought into contact with each other directly or through the reflection sheet.
According to a sixth aspect of the present invention, there is provided a surface illuminator including:
a single or a plurality of aperture fluorescent lamps having a phosphor layer formed on an inner surface of a glass tube, and an aperture portion formed by eliminating the phosphor layer in a predetermined region in an axial direction of the glass tube and opened for light projection, the single or the plurality of aperture fluorescent lamps being disposed on a surface roughly parallel to a light emission surface of the surface illuminator, wherein:
each of the aperture fluorescent lamps has two aperture portions, each having a belt-like shape, disposed around an axis of the aperture fluorescent lamp to be separated from each other by a predetermined angle gap; and each of the aperture fluorescent lamps is disposed while a symmetry axis of a cross section of the aperture fluorescent lamp passing through a middle part of the two aperture portions is directed in a direction roughly vertical to the light emission surface.
According to a seventh aspect of the present invention, there is provided a surface illuminator including:
a single or a plurality of aperture fluorescent lamps having an aperture portion disposed on a surface roughly parallel to a light emission surface to be directed in a direction roughly perpendicular to the light emission surface, wherein;
the aperture fluorescent lamp includes a glass tube having an inner diameter set equal to about 3 mm or less.
According to a eighth aspect of the present invention, there is provided a surface illuminator including:
an aperture fluorescent lamp having a glass tube, a pair of electrodes sealed to both ends of the glass tube, a phosphor layer formed on an inner surface of the glass tube, and an aperture portion formed by eliminating the phosphor layer in a predetermined region in an axial direction of the glass tube and opened for light projection; and
a holding frame member for holding the aperture fluorescent lamp through a supporting member, wherein
a lead conductor connected to the electrode has a tip part machined in a predetermined convex shape, the supporting member has a pair of concaves or a pair of hole parts to be fitted to the tip part of the lead conductor, and the tip part and the concaves or the hole parts are machined to fix the aperture fluorescent lamp in a fitted state while the aperture portion is directed in a predetermined direction.
According to a ninth aspect of the present invention, there is provided a liquid crystal display device, including:
a surface illuminator specified above; and
a liquid crystal panel.
According to a tenth aspect of the present invention, there is provided an electronic device, including a liquid crystal display device specified above.
With the above configurations, since the phosphor is exfoliated by using the thread-like member or the belt-like member, even in the case of the small-diameter glass tube having the inner diameter set equal to, for example, 3 mm or less, the aperture portion can be easily and accurately formed at low cost and with high reliability.
Even in the case of the glass tube having a long tube length, the aperture portion can be easily and accurately formed at low cost and with high reliability.
By using the small-diameter aperture fluorescent lamp, luminance efficiency can be increased.
By using the small-diameter aperture fluorescent lamp, a thin, narrow-frame and lightweight surface illuminator can be provided. By using the surface illuminator, a thin, narrow-frame and lightweight liquid crystal display device can be provided. By using this liquid crystal display device, a thin, narrow-frame and lightweight electronic device can be provided.
In addition, the aperture portion can be easily and surely positioned only by fitting the tip part of the lead conductor machined in a predetermined convex shape in the concave or hole part of the supporting member. Thus, work efficiency can be increased, yield can be improved, and work automation can be dealt with.
By using the small-diameter aperture fluorescent lamp, even in the case of a surface illuminator of the directly-below type, a thin and lightweight surface illuminator can be provided.
Furthermore, in the surface illuminator of the directly-below type, a plurality of the aperture fluorescent lamps having two aperture portions separated from each other by a predetermined angle gap around the axis are arrayed. Thus, the surface illuminator can be improved in luminance uniformity, and can be made thin and lightweight.